The sex organs in fungi are called gametangia (sing. gametangium), and may be differentiated into distinguishable male and female organs that bear either differentiated sex cells (gametes) or one or more "gamete nuclei.”
If a single mycelium is capable of reproducing sexually it is homothallic
if two mycelia are required to reproduce sexually, they are heterothallic. Heterothallic forms may have both male and female gametangia on the same mycelium, but they are incompatible with one another.